| 摘要 |
PURPOSE:To always execute a state change detection of each slave station at least one within a prescribed time by the state change detection by dividing the remaining slave stations into several stations each, at the time of a transmitting interruption of a priority data from some slave station, when executing a remote supervision and control of 1:N. CONSTITUTION:A master station 10 executes a remote supervision of slave stations 7a-7e by a changeover switch (SW)11 and a circuit 9. For instance, when the salve station 7a is transmitting a priority data, the transmission is suspended at every prescribed time, other slave stations 7b-7e are divided into plural stations each in the course of a transmission downtime and the changeover switch 11 is switched, and presence or absence of a state change signal is checked. Subsequently, a priority data transmission of the slave station 7a is restarted. When the priority data transmission of the salve station 7a is ended, the SW11 is switched to the slave station 7b, and in the same way, the transmission from the slave station 7b is received. The priority data transmission time of once is shortened in advance. In this way, the state change of all the slave stations is always detected at least one within a prescribed time, a detection delay of the state change is prevented, and the time when updating of a data of the priority transmission stops is shortened.
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